1. Field of the Invention
Method of Using Same to Transform Sludge into an Ecologically Acceptable Material.
2. Description of the Prior Art
In the past, it has been known that quick lime and slacked lime have a tendency to solidify sewage sludge, organic sludge including oil waste, and marine silt when mixed therewith. However, prior to the present invention no apparatus has been available to mechanically mix metered quantities of calcium oxide with viscous asphalt-like material when it is in a sump to cause the solidification thereof, and the solidified material having toxic compounds of metals such as cadmium, chromium, arsenic and zinc locked therein in an insoluble form.
Likewise, prior to the present invention no known process or apparatus has been available by which hydrocarbon bearing sludges and hazardous marine silt as well as sewage sludge or other toxic sludges containing a substantial quantity of water is sequentially subjected to the action of calcium oxide at a metered rate in a confined space to initiate an exothermic reaction in which the temperature of the sludge-calcium oxide mixture rises with the evolution of substantial quantities of steam. Neutralization, agglomeration and base exchange occurs in the confined space as the exothermic reaction proceeds, with the pH of the sludge-calcium oxide mixture rising to at least 12.4. As the calcium oxide dissolves in the aqueous sludge, dehydration of the sludge occurs with an increase in temperature and bacteria and virus present in the sludge are destroyed due to this increase in temperature and the high pH of the resulting calcium oxide sludge mixture are destroyed. The calcium oxide as it dissolves results in the formation of hydrates that tend to bind solid particles in the sludge together to form agglomeration of particles. The increase in pH previously mentioned results in soluble toxic salts of the metals previously mentioned being transformed into insoluble compounds. The reaction product discharges from the confined space as relatively hard friable particles that are still hot and steaming, and substantially free of odor, and that have toxic metals locked therein in an insoluble form. The reaction product retains a substantial quantity of initially present water as an integral part thereof. The reaction product may be compacted and is suitable for landfill, road bed use, and, if neutralized, may be used for agricultural and other purposes,
A major object of the present invention is to provide a method that in conjunction with calcium oxide may be used to solidify the contents of oil sludge sumps, and also process and apparatus that is adapted to have sludge of industrial or municipal origin, as well as hazardous marine silt, discharged thereto to be transformed into solid ecologically acceptable material.